Escherichia coli O-Antigen Gene Clusters of Serogroups O62, O68, O131, O140, O142, and O163: DNA Sequences and Similarity between O62 and O68, and PCR-Based Serogrouping
Yanhong Liu,
Xianghe Yan,
Chitrita DebRoy,
Pina M. Fratamico,
David S. Needleman,
Robert W. Li,
Wei Wang,
Liliana Losada,
Lauren Brinkac,
Diana Radune,
Magaly Toro,
Narasimha Hegde,
Jianghong Meng
Affiliations
Yanhong Liu
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA
Xianghe Yan
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA
Chitrita DebRoy
Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802, USA
Pina M. Fratamico
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA
David S. Needleman
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA
Robert W. Li
Animal Genomics and Improvement Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA
Wei Wang
Craig Venter Institute, Rockville, MD 20850, USA
Liliana Losada
Craig Venter Institute, Rockville, MD 20850, USA
Lauren Brinkac
Craig Venter Institute, Rockville, MD 20850, USA
Diana Radune
Craig Venter Institute, Rockville, MD 20850, USA
Magaly Toro
Department of Nutrition & Food Science, University of Maryland, College Park, MD 20742, USA
Narasimha Hegde
Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802, USA
Jianghong Meng
Department of Nutrition & Food Science, University of Maryland, College Park, MD 20742, USA
The DNA sequence of the O-antigen gene clusters of Escherichia coli serogroups O62, O68, O131, O140, O142, and O163 was determined, and primers based on the wzx (O-antigen flippase) and/or wzy (O-antigen polymerase) genes within the O-antigen gene clusters were designed and used in PCR assays to identify each serogroup. Specificity was tested with E. coli reference strains, field isolates belonging to the target serogroups, and non-E. coli bacteria. The PCR assays were highly specific for the respective serogroups; however, the PCR assay targeting the O62 wzx gene reacted positively with strains belonging to E. coli O68, which was determined by serotyping. Analysis of the O-antigen gene cluster sequences of serogroups O62 and O68 reference strains showed that they were 94% identical at the nucleotide level, although O62 contained an insertion sequence (IS) element located between the rmlA and rmlC genes within the O-antigen gene cluster. A PCR assay targeting the rmlA and rmlC genes flanking the IS element was used to differentiate O62 and O68 serogroups. The PCR assays developed in this study can be used for the detection and identification of E. coli O62/O68, O131, O140, O142, and O163 strains isolated from different sources.
